In a blistering white paper published the same day that a new poll put Carson atop his GOP challengers in Iowa, the Club for Growth accused Carson of holding anti-capitalist positions and said it did not believe he would be a “pro-growth” president.

Specifically, they take aim at Carson's health policy that would create government-backed health savings accounts for Americans at birth. Carson’s plan would allow Americans to make pre-tax contributions to their accounts.

The Club for Growth argued that the government shouldn't have a role in the healthcare market at all. They pointed out that Carson's 2012 book “America The Beautiful,” advocated for making insurance companies “non-profit service organizations with standardized, regulated profit margins.”

The Club called the position a “de facto nationalization of private companies [that] would be extremely anti-growth and a direct assault on economic liberty.”

“Carson's advocacy for it raises serious questions about his understanding of the problem of government overreach,” it said.

A spokesman for Carson’s campaign suggested the Club had decided it wouldn’t back Carson, and wrote a white paper on his economic policies to match its politics.

“Easy for them to write when they knew from the start how they wanted their analysis to end,” Carson Communications Director Dough Watts told the Washington Examiner.

“The club never reached out to our campaign, never solicited our views, never asked for a meeting with Dr. Carson. It is the club and it is only interested in the growth of their own power.”

Carson, a retired neurosurgeon, has captured the imagination of the right's grassroots. The Club's criticism of his conservative principles could prove a hurdle for him if he hopes to keep support amongst the party's base.